Satelitte Cloud Maps and Selection of the Sites for Astronomical Observation in Yunnan

On the basis of the 1.1 km equal longitude and latitude projection and the corrections for calibration and fixed position from the cloud maps of the meteorological satelittes NOAA-10 and 11 obtained from May 1989 to April 1990, the cloud maps of 31 candidate sites(E 99 °-104 °N 23.5 °-28.5 °)are calculated by using the method of infrared threshod value and a statistical analysis is made. Several candidate sites with the least cloud are obtained. In addition, the correlative analysis is also made between the total numbers of clear days and nights with CC≤3 according to the satelittes and those with CC≤2 from the ground-based observation of 30 years. A good correlation between them is found. The analysis of the satelitte cloud maps and the ground-based observations of thirty years shows that.(1) Wonidaobo of Yongren County, Laoguanshang of Yaoan County, Bailu of Yuanmou County, Dayinhoushan of Xiangyun County, Xiaojishan of Binchuan County, Muogushan of Huaping County and Taerbuzi of Ninglang County in Yunnan Province are all good candidates.(2) Each of three candidate ones among the above-mentioned sites, i.e. Wonidaobo, Laoguangshan and Bailu may have over 250 nights which can be used to observe stars, from our estimate.